Development of an Arrayed Tactile Sensor Having Four Stories and Recognition of Contact State Using Neural Networks

Abstract

In the human skin, four kinds of tactile receptors are distributed three dimensionally, i.e., not only on the skin surface but also in the four corresponding depths of the skin. Imitating this, a tactile sensor having four stories is proposed, inside each story of which capacitive force sensing elements are distributed in an array. The recognition method of contact state using neural networks is proposed. The stress distribution of a sensor sheet is obtained, and the outputs of the sensing elements are simulated by FEM. By applying the outputs to neural networks, it is confirmed that the contact shape recognition is possible, and the sensor having four stories achieves higher recognition rate compared with that having one story. The MEMS fabrication method of an arrayed capacitive tactile sensor made of PDMS is proposed, in which Parylene is used as an anti-stiction layer for the purpose of peeling off the PDMS sheet easily from the substrate. By stacking this sensor one by one, fabrication of a sensor having four stories is possible. A sensor having one story is preliminarily fabricated. The basic performance of one force sensing element and that of an arrayed sensor composed of 3×3 elements are characterized, which shows the potential of the proposed sensor for tactile sensing.